Electric fuse-plug.



T. E MURRAY. ELECTRIC FUSE PLUG. APPUCAHON FILED 050.29. ms.

moans a. norm, or new YORK, 11. Y.

anionic FUSE-PLUG.

Specification of Letters Intent.

Patented Mar. 12, 1918.

Application filed December 29, 1916. Serial No. 189,503.

To all whom it may concern:

- Be it known that I, THoMn-s E. MURRAY, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented acertain new and useful Improvement in Electric Fuse-Plugs, of which the following is a specification.

The invention is an electric fuse plug of the-type wherein the contacts are respectively a threaded external shell and a plate at one end of said plug, and the fuse connecting said contacts is embedded in a mass of insulating material; and the said invention consists in the construction, more particularly hereinafter set forth, whereby the cap or cover of said plug is held in place, and the mode in which the fuse is embedded in the insulating mass.

In the accompanying dra'wings- Figure 1 is a section of my fuse plug. Fig. 2 is a similar section of said plug,

showing the insulating mass in two layers respectively of dense solid and dry comminuted materials. Fig. 3 is a side view of the metal cap.

Similar letters of reference indicate like parts.

-G and a flange I-I around said opening.

Said flange may he indented at its edge.

. The teeth thus formed are spread outwardly.

There is a recess I, Fig. 3, in said flange through which the fuse strip E passes when the cap is in place. r

The fuse strip E is wholly en'ibedded in the core, and so also is the flange of cap F. lhe projection D is also embedded, together with a portion of the contact C. Between the upper edge of shell B and the bottom of cap 1*, and between the lower edge of shell B and contact C there are spaces which are filled with the material of the core A, said shell being thus insulated from said cap and said contact.

Instead of making the core A wholly of plaster or other solid insulating material, I may make the core in two sections, as shown in Fig. 2, the upper section J and the lower section K only being of plaster. Between said sections, I place a layer L of comminuted refractory insulating material, such as dry plaster, which section L incloses' the blowing point M of the fuse strip, so that said comminuted material first receives the explosion and acts to dampen the shock thereof.

In making my fuse, I proceed as follows:

In a block N of any suitable solid material 1 form a recess approximating the shape of the plug. In said recess I place a lining O of. metal internally threaded and conforming to the shape of shell 13. I connect the fuse strip at its ends, as described, to the contact (J and shell B, and place these parts in said recess. 1 then apply the cap F, which covers said recess and rests on the top of block N. I then prepare the material for the core in fluid form. In using plaster, I mix the dry material with water to make a freely flowing liquid which I pour into the recess through the opening (Jr in cap F. Said liquid then fills said recess, and also the spaces or interstices between the ends of shell B and contact C and cap F. When the plaster has set and become hard, I remove the plug from the mold.

The flared flange H on cap'F being embedded in the hardened plaster, holds said cap firmly in place and prevents its removal.

In making the modified form of fuse plu shown in Fig. 2, I place thecontact C an shell B in the block recess, as already described, and then without applying the cap, I pour the liquid insulating material .into the recess until the lower section K of suitable depth is formed; I then introduce the layer L of dry comminuted material, and

afiix the cap, pushing the flared flange H down into the comminuted mass until the cap rests on the block .N. Finally, I pour in the liquid insulating. material to formthe upper section J of the core through the opening G in the cap.

I claim:

1. A fuse plug of the type wherein the contacts are respectively a threaded shell and a plate at one end of said plu and the fuse connecting said contacts is em dded in a mass of insulating material, the combina} tion of a cover cap for said plug having a central opening. and a flange around said opening, the saidfiange being embedded in said insulating mass.

2. A fuse plug, as in claim 1, the said tacts end having an opening for the passagefla-nge being outwardly flared, and the said )1? the fuse. 10 insulating mass being of a material hard- In testimony whereof I have afiixed my ened by setting around and engaging said signature in presence of two witnesses. 5 flared flange to lock said cap in place on THOMAS E. MURRAY.

said plug. Witnesses:

3. A fuse plug, as in claim 1, the said GERTRUDE T. PORTER,

.fiange being interposed between said con- MAY T. MCGARRY. 

